A common practice in forming fibers of mineral material, such as glass, is to discharge molten glass from a forehearth into a rotating centrifuge or spinner. The molten glass flows across the spinner bottom wall to the spinner sidewall and passes in a molten state through the orifices of the spinner sidewall to create primary fibers. Thereafter, the primary fibers can be further attenuated into a veil of secondary fibers of smaller diameter by the action of a downward flow of gases from an annular blower. Hot gases from an annular burner maintain the spinner sidewall at a temperature suitable for centrifuging the glass. The hot gases from the burner also maintain the primary fibers emanating from the spinner in a plastic state to enable further attenuation into secondary fibers. The fiber forming process is regulated by controlling the various process variables, such as the temperature or volume of hot gases from the burner, the pressure of the air from the blower, the molten glass temperature and viscosity, and the rotation rate of the spinner.
One of the problems associated with operating glass fiber forming operations is the inability to accurately assess process conditions, such as the spinner wall temperature, molten glass thickness on the interior of the spinner wall, and air pressure at the spinner wall, under the extreme conditions associated with forming fibers from molten glass. It is extremely difficult, for example, to accurately monitor the temperature of the spinner sidewall during operation. The measurement of the temperature profile of the spinner sidewall is important because the sidewall temperature determines, in part, fiber diameters and other fiber qualities.
Attempts to assess the temperature profile of the spinner sidewall, bottom wall, and top flange have not been entirely successful. The spinner temperature profile is further complicated by the fact that the hot gases from the burner are mixed with the relatively cool gases from the blower and the cool air induced by the blower to form a complex temperature profile pattern. The spinner itself is rotating at a rate of over 2000 r.p.m., and the sidewall temperature is in the vicinity of 1700.degree. F. (925.degree. C.) or higher. Attempts to position thermocouples or other process monitoring devices on the spinner itself have not been successful due to the extreme environmental conditions in which the spinner operates, and the inability to effectively transmit data from a sensing device to a non-rotating control apparatus. An optical pyrometer has also been used, but this has provided only obscure and unusable results. There is a need for means for more accurately assessing temperature profiles on rotating spinners. There is also a need for an improved ability to monitor other process conditions on rotating spinners.